Pluripotent Human Embryonic Stem Cells Research Articles

A Method to Identify and Isolate Pluripotent Human Stem Cells and Mouse Epiblast Stem Cells Using Lipid Body-Associated Retinyl Ester Fluorescence

We describe the use of a characteristic blue fluorescence to identify and isolate pluripotent human embryonic stem cells and human-induced pluripotent stem cells. The blue fluorescence emission (450–500 nm) is readily observed by fluorescence microscopy and correlates with the expression of pluripotency markers (OCT4, SOX2, and NANOG). It allows easy identification and isolation of undifferentiated human pluripotent stem cells, high-throughput fluorescence sorting and subsequent propagation. The fluorescence appears early during somatic reprogramming. We show that the blue fluorescence arises from the sequestration of retinyl esters in cytoplasmic lipid bodies. The retinoid-sequestering lipid bodies are specific to human and mouse pluripotent stem cells of the primed or epiblast-like state and absent in naive mouse embryonic stem cells. Retinol, present in widely used stem cell culture media, is sequestered as retinyl ester specifically by primed pluripotent cells and also can induce the formation of these lipid bodies.

Aspirin Enhances Osteogenic Potential of Periodontal Ligament Stem Cells (PDLSCs) and Modulates the Expression Profile of Growth Factor-Associated Genes in PDLSCs.

This study investigates the effects of aspirin (ASA) on the proliferative capacity, osteogenic potential, and expression of growth factor-associated genes in periodontal ligament stem cells (PDLSCs). Mesenchymal stem cells (MSCs) from PDL tissue were isolated from human premolars (n = 3). The MSCs' identity was confirmed by immunophenotyping and trilineage differentiation assays. Cell proliferation activity was assessed through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Polymerase chain reaction array was used to profile the expression of 84 growth factor-associated genes. Pathway analysis was used to identify the biologic functions and canonic pathways activated by ASA treatment. The osteogenic potential was evaluated through mineralization assay. ASA at 1,000 μM enhances osteogenic potential of PDLSCs. Using a fold change (FC) of 2.0 as a threshold value, the gene expression analyses indicated that 19 genes were differentially expressed, which includes 12 upregulated and seven downregulated genes. Fibroblast growth factor 9 (FGF9), vascular endothelial growth factor A (VEGFA), interleukin-2, bone morphogenetic protein-10, VEGFC, and 2 (FGF2) were markedly upregulated (FC range, 6 to 15), whereas pleotropin, FGF5, brain-derived neurotrophic factor, and Dickkopf WNT signaling pathway inhibitor 1 were markedly downregulated (FC 32). Of the 84 growth factor-associated genes screened, 35 showed high cycle threshold values (≥35). ASA modulates the expression of growth factor-associated genes and enhances osteogenic potential in PDLSCs. ASA upregulated the expression of genes that could activate biologic functions and canonic pathways related to cell proliferation, human embryonic stem cell pluripotency, tissue regeneration, and differentiation. These findings suggest that ASA enhances PDLSC function and may be useful in regenerative dentistry applications, particularly in the areas of periodontal health and regeneration.

Impact of transient down-regulation of DREAM in human embryonic stem cell pluripotency: The role of DREAM in the maintenance of hESCs

Little is known about the functions of downstream regulatory element antagonist modulator (DREAM) in embryonic stem cells (ESCs). However, DREAM interacts with cAMP response element-binding protein (CREB) in a Ca2+-dependent manner, preventing CREB binding protein (CBP) recruitment. Furthermore, CREB and CBP are involved in maintaining ESC self-renewal and pluripotency. However, a previous knockout study revealed the protective function of DREAM depletion in brain aging degeneration and that aging is accompanied by a progressive decline in stem cells (SCs) function. Interestingly, we found that DREAM is expressed in different cell types, including human ESCs (hESCs), human adipose-derived stromal cells (hASCs), human bone marrow-derived stromal cells (hBMSCs), and human newborn foreskin fibroblasts (hFFs), and that transitory inhibition of DREAM in hESCs reduces their pluripotency, increasing differentiation. We stipulate that these changes are partly mediated by increased CREB transcriptional activity. Overall, our data indicates that DREAM acts in the regulation of hESC pluripotency and could be a target to promote or prevent differentiation in embryonic cells.

Pluripotent Human embryonic stem cell derived neural lineages for in vitro modelling of enterovirus 71 infection and therapy.

BackgroundThe incidence of neurological complications and fatalities associated with Hand, Foot & Mouth disease has increased over recent years, due to emergence of newly-evolved strains of Enterovirus 71 (EV71). In the search for new antiviral therapeutics against EV71, accurate and sensitive in vitro cellular models for preliminary studies of EV71 pathogenesis is an essential prerequisite, before progressing to expensive and time-consuming live animal studies and clinical trials.MethodsThis study thus investigated whether neural lineages derived from pluripotent human embryonic stem cells (hESC) can fulfil this purpose. EV71 infection of hESC-derived neural stem cells (NSC) and mature neurons (MN) was carried out in vitro, in comparison with RD and SH-SY5Y cell lines.ResultsUpon assessment of post-infection survivability and EV71 production by the various types, it was observed that NSC were significantly more susceptible to EV71 infection compared to MN, RD (rhabdomyosarcoma) and SH-SY5Y cells, which was consistent with previous studies on mice. The SP81 peptide had significantly greater inhibitory effect on EV71 production by NSC and MN compared to the cancer-derived RD and SH-SY5Y cell lines.ConclusionsHence, this study demonstrates that hESC-derived neural lineages can be utilized as in vitro models for studying EV71 pathogenesis and for screening of antiviral therapeutics.

Identification of polymer surface adsorbed proteins implicated in pluripotent human embryonic stem cell expansion.

Improved biomaterials are required for application in regenerative medicine, biosensing, and as medical devices. The response of cells to the chemistry of polymers cultured in media is generally regarded as being dominated by proteins adsorbed to the surface. Here we use mass spectrometry to identify proteins adsorbed from a complex mouse embryonic fibroblast (MEF) conditioned medium found to support pluripotent human embryonic stem cell (hESC) expansion on a plasma etched tissue culture polystyrene surface. A total of 71 proteins were identified, of which 14 uniquely correlated with the surface on which pluripotent stem cell expansion was achieved. We have developed a microarray combinatorial protein spotting approach to test the potential of these 14 proteins to support expansion of a hESC cell line (HUES-7) and a human induced pluripotent stem cell line (ReBl-PAT) on a novel polymer (N-(4-Hydroxyphenyl) methacrylamide). These proteins were spotted to form a primary array yielding several protein mixture 'hits' that enhanced cell attachment to the polymer. A second array was generated to test the function of a refined set of protein mixtures. We found that a combination of heat shock protein 90 and heat shock protein-1 encourage elevated adherence of pluripotent stem cells at a level comparable to fibronectin pre-treatment.

A scalable label-free approach to separate human pluripotent cells from differentiated derivatives.

The broad capacity of pluripotent human embryonic stem cells (hESC) to grow and differentiate demands the development of rapid, scalable, and label-free methods to separate living cell populations for clinical and industrial applications. Here, we identify differences in cell stiffness, expressed as cell elastic modulus (CEM), for hESC versus mesenchymal progenitors, osteoblast-like derivatives, and fibroblasts using atomic force microscopy and data processing algorithms to characterize the stiffness of cell populations. Undifferentiated hESC exhibited a range of CEMs whose median was nearly three-fold lower than those of differentiated cells, information we exploited to develop a label-free separation device based on the principles of tangential flow filtration. To test the device's utility, we segregated hESC mixed with fibroblasts and hESC-mesenchymal progenitors induced to undergo osteogenic differentiation. The device permitted a throughput of 10(6)-10(7) cells per min and up to 50% removal of specific cell types per single pass. The level of enrichment and depletion of soft, pluripotent hESC in the respective channels was found to rise with increasing stiffness of the differentiating cells, suggesting CEM can serve as a major discriminator. Our results demonstrate the principle of a scalable, label-free, solution for separation of heterogeneous cell populations deriving from human pluripotent stem cells.

Keeping a lid on nodal: transcriptional and translational repression of nodal signalling.

Nodal is an evolutionarily conserved member of the transforming growth factor-β (TGF-β) superfamily of secreted signalling factors. Nodal factors are known to play key roles in embryonic development and asymmetry in a variety of organisms ranging from hydra and sea urchins to fish, mice and humans. In addition to embryonic patterning, Nodal signalling is required for maintenance of human embryonic stem cell pluripotency and mis-regulated Nodal signalling has been found associated with tumour metastases. Therefore, precise and timely regulation of this pathway is essential. Here, we discuss recent evidence from sea urchins, frogs, fish, mice and humans that show a role for transcriptional and translational repression of Nodal signalling during early development.

The New Federalism: State Policies Regarding Embryonic Stem Cell Research.

Stem cell policy in the United States is an amalgam of federal and state policies. The scientific development of human pluripotent embryonic stem cells (ESCs) triggered a contentious national stem cell policy debate during the administration of President George W. Bush. The Bush "compromise" that allowed federal funding to study only a very limited number of ESC derived cell lines did not satisfy either the researchers or the patient advocates who saw great medical potential being stifled. Neither more restrictive legislation nor expansion of federal funding proved politically possible and the federal impasse opened the door for a variety of state-based experiments. In 2004, California became the largest and most influential state venture into stem cell research by passing "Prop 71," a voter initiative that created a new stem cell agency and funded it with $3 billion. Several states followed suit with similar programs to protect the right of investigators to do stem cell research and in some cases to invest state funding in such projects. Other states devised legislation to restrict stem cell research and in five states, criminal penalties were included. Thus, the US stem cell policy is a patchwork of multiple, often conflicting, state and federal policies.

Human-Mouse Chimerism Validates Human Stem Cell Pluripotency

SummaryPluripotent stem cells are defined by their capacity to differentiate into all three tissue layers that comprise the body. Chimera formation, generated by stem cell transplantation to the embryo, is a stringent assessment of stem cell pluripotency. However, the ability of human pluripotent stem cells (hPSCs) to form embryonic chimeras remains in question. Here we show using a stage-matching approach that human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) have the capacity to participate in normal mouse development when transplanted into gastrula-stage embryos, providing in vivo functional validation of hPSC pluripotency. hiPSCs and hESCs form interspecies chimeras with high efficiency, colonize the embryo in a manner predicted from classical developmental fate mapping, and differentiate into each of the three primary tissue layers. This faithful recapitulation of tissue-specific fate post-transplantation underscores the functional potential of hPSCs and provides evidence that human-mouse interspecies developmental competency can occur.

Enhanced Differentiation of Human Embryonic Stem Cells Toward Definitive Endoderm on Ultrahigh Aspect Ratio Nanopillars

Differentiation of human embryonic stem cells is widely studied as a potential unlimited source for cell replacement therapy to treat degenerative diseases such as diabetes. The directed differentiation of human embryonic stem cells relies mainly on soluble factors. Although, some studies have highlighted that the properties of the physical environment, such as substrate stiffness, affect cellular behavior. Here, mass‐produced, injection molded polycarbonate nanopillars are presented, where the surface mechanical properties, i.e., stiffness, can be controlled by the geometric design of the ultrahigh aspect ratio nanopillars (stiffness can be reduced by 25.0003). It is found that tall nanopillars, yielding softer surfaces, significantly enhance the induction of definitive endoderm cells from pluripotent human embryonic stem cells, resulting in more consistent differentiation of a pure population compared to planar control. By contrast, further differentiation toward the pancreatic ­endoderm is less successful on “soft” pillars when compared to “stiff” pillars or control, indicating differential cues during the different stages of differentiation. To accompany the mechanical properties of the nanopillars, the concept of surface shear modulus is introduced to describe the characteristics of engineered elastic surfaces through micro or nanopatterning. This provides a framework whereby comparisons can be drawn between such materials and bulk elastomeric materials.

Abstract A15: A human mini brain model of pediatric GBM

Abstract Glioblastoma (GBM) is the most devastating brain cancer with dismal prognosis both in adults and children and accounts for 16% of primary brain tumors. Despite aggressive therapeutic approaches, the majority of patients die within one year after diagnosis. Giving the limitation of current GBM mouse models, which do not reflect the biological properties of human tumors, in particular, tumor heterogeneity and pathogenesis, there is a growing need for new models. Current in vitro 3D models involve the use of hydrogel scaffolds and cell lines, which do not represent a viable developmental context where the tumor mass interacts with and invades the surrounding brain tissues. Starting with pluripotent human embryonic stem cells we reproduced a 3D tissue structure (so-called cerebral organoid) representing a developing human brain in vitro. We engineered these mini-brains to express oncogenic hits responsible for the derivation of tumors in pediatric GBM patients. Pediatric GBM is driven by a combination of epigenetic and genetic hits including the expression of a mutant histone H3 variant H3F3A (mutated at K27M or G34R) or a gain of function mutant isocitrate dehydrogenase IDH1R132H in combination with the loss of the histone remodeling factor ATRX and/or p53 tumor suppressor. We used a combination of these oncogenic hits to create a model of tumor engineering representing the first 3D human tissue model of GBM. This model combines the accurate multi-lineage differentiation and physiology of human brain with the easiness of manipulation of in vitro systems. H&E staining of the modified organoids shows remarkable dysplasia reminiscent of human primary glioma. Different genetic hits result in different type of dysplasia with IDH1R132H showing distinct morphology, suggestive of a broad range of applicability to model oncogenic-dependence in pediatric GBM. Cerebral organoids may also be used as a model to study tumor invasion starting with glioma stem-like cells (GSCs, which are believed to be the tumor-initiating cells in GBM). Indeed 923 GSCs (which are not invasive in mice brain) quickly and spontaneously (within few days) invade a co-cultured cerebral organoid. This study is the first to engineer a human CNS tumor in vitro. The model carries a tremendous potential to uncover the pathogenesis and initiation of brain cancer in a pediatric setting. Note: This abstract was not presented at the conference. Citation Format: Amin Ismail. A human mini brain model of pediatric GBM. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A15.

Abstract 18901: Endothelium Based Feeder Improves Capacity of Human Embryonic Stem Cells Derived Cardiomyocytes

Introduction: The regenerative ability of the heart is very low, making patients with myocardial damage potential candidates for cell-based regenerative therapy. Pluripotent human embryonic stem cells (hESC) are a promising source of cardiomyocytes (CMs). While the quantity of CMs obtained is no longer a limitation in current differentiation protocols, their functionality remains to be improved. Indeed contracting areas in cell cultures are still heterogeneous and non-consistent Hypothesis: Endothelial cells (ECs) and CMs are derived from a common precursor. Moreover, endothelial secreted and contact dependent factors play a role at different phases of cardiac development and repair. We hypothesized that creating a mixture of cell types that more closely resembles heart tissue - i.e. containing both ECs and CMs - will lead to improved maturation and functionality Methods: We co-cultured NKX2-5-GFP reporter hESC line and an autonomous Akt-activated ECs and induced differentiation of NKX2-5GFP hESC into CMs We assessed functionality by evaluating beating and coordination between different CMs clusters. Results: Around 94% ± 6 of the NKX2-5GFP+ cells were beating when hESCs embryonic body (EBs) were plated on E4+ECs comparing to 34% ± 12.9 for controls. The spatial organization of beating areas in co-cultures was different. In 7 different experiments clustered in two populations, the average BPM of CMs in co-culture was faster and closer to a physiologic heart rate compare to controls (49.6 ± 13.77; n=13 vs 24.76 ±9.36; n=8 for controls; p<0.05). Our protocol increased and accelerated the differentiation of CMs. More importantly CMs formed under these conditions displayed a higher rate of contractility with synchronized beating relying on an endothelial network. Conclusions: We have been able to build a culture platform in vitro capturing partially complexity of cardiac tissue. Such strategy resulted in the obtaining of more synchronized interconnected CMs nodes displaying faster beating. Our data showed that co-culture of differentiating hESCs with ECs increased functionality of the CMs, suggesting that an endothelial based feeder could promote the in vitro functionalization of clinically relevant cell type.

A comparison of genetically matched cell lines reveals the equivalence of human iPSCs and ESCs.

The equivalence of human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) remains controversial. Here we use genetically matched hESC and hiPSC lines to assess the contribution of cellular origin (hESC vs. hiPSC), the Sendai virus (SeV) reprogramming method and genetic background to transcriptional and DNA methylation patterns while controlling for cell line clonality and sex. We find that transcriptional and epigenetic variation originating from genetic background dominates over variation due to cellular origin or SeV infection. Moreover, the 49 differentially expressed genes we detect between genetically matched hESCs and hiPSCs neither predict functional outcome nor distinguish an independently derived, larger set of unmatched hESC and hiPSC lines. We conclude that hESCs and hiPSCs are molecularly and functionally equivalent and cannot be distinguished by a consistent gene expression signature. Our data further imply that genetic background variation is a major confounding factor for transcriptional and epigenetic comparisons of pluripotent cell lines, explaining some of the previously observed differences between genetically unmatched hESCs and hiPSCs.

The knockdown of H19lncRNA reveals its regulatory role in pluripotency and tumorigenesis of human embryonic carcinoma cells.

The function of imprinted H19 long non-coding RNA is still controversial. It is highly expressed in early embryogenesis and decreases after birth and re-expressed in cancer. To study the role of H19 in oncogenesis and pluripotency, we down-regulated H19 expression in vitro and in vivo in pluripotent human embryonic carcinoma (hEC) and embryonic stem (hES) cells. H19 knockdown resulted in a decrease in the expression of the pluripotency markers Oct4, Nanog, TRA-1-60 and TRA-1-81, and in the up-regulation of SSEA1; it further attenuated cell proliferation, decreased cell-matrix attachment, and up-regulated E-Cadherin expression. SCID-Beige mice transplanted with H19 down-regulated hEC cells exhibited slower kinetics of tumor formation, resulting in an increased animal survival. Tumors derived from H19 down-regulated cells showed a decrease in the expression of pluripotency markers and up-regulation of SSEA-1 and E-cadherin. Our results suggest that H19 oncogenicity in hEC cells is mediated through the regulation of the pluripotency state.

Abnormal expression of genes governing adipogenesis and extracellular matrix (ECM) formation in subcutaneous (SC) abdominal adipose stem cells (ASCs) of lean polycystic ovary syndrome (PCOS) women

from four lean (body mass index: 19-25 kg/m 2 )P COS women, ages 21-32 years, and four BMI- and age-matched NL women. ASCs were isolated after digestion of SC abdominal adipose with collagenase and differential centrifugation. RNA from ASCs was extracted using Qiagen miRNeasy Mini Kit. Microarray and small non-coding RNA (miRNA) analysis were performed using Affymetrix Human Genome U1.33 2.0 and Human miRNA arrays, respectively. Data were analyzed using Ingenuity Pathway Analysis. RESULTS: Differential expression of >1.5 fold change between SC abdominal ASCs of PCOS and NL women indicated 64 up-regulated and 103 down-regulated genes (P<0.05). Nine genes involving adipogenesis were up-regulated (WARS2, CXCL5, CYP26B1, CYP4V2, TBX3, GPX3, CXCL2, SCD and APOC1) and 6 genes were down-regulated (HHIP, WNT5A, WISP1, SEMA3A, ITGA6 and GREM1). Differential canonical pathways between the two female groups included (i) Liver X Receptor/Retinoid X Receptor (LXR/RXR) activation (P¼0.001), (ii) Notch signaling (P¼0.002), (iii) epithelial-mesenchymal regulation (P¼0.006), (iv) Vitamin D Receptor/ Retinoid X Receptor (VDR/RXR) activation (P¼0.013) and (v) human embryonic stem cell pluripotency (P¼0.05), all of which involve adipogenesis and ECM formation. TGFb1 was identified as the master upstream regulatory gene (P¼0.004), governing genes affecting adipogenesis (SCD, TBX3, WNT5A, ITGA6, SEMA3A and WISP1) and ECM formation (CH13L1, TNC, MYO10, JAG1, SOX4 and ANKRD1). Interestingly, miRNA array identified miRNAs controlling gene regulation of adipogenesis and ECM formation, including hsa-miR-4709-3p (GREM1 and SEMA3A), hsa-miR-532-3p (CYP26B1), hsa-miR-532-5p (CXCL2), hsa-miR-23c (WARS2), hsa-miR-299-5p (SOX4) and hsa-miR-298 (GPX3 )( P<0.05). The last 3 of these miRNAs also have been shown to be differentially expressed in PCOS 1 . CONCLUSIONS: A network of interrelated genetic pathways in SC abdominal ASCs offers a developmental programming model for PCOS through regulation of adipogenesis and ECM. Reference: 1. Sorensen AE, Wissing ML, Salo S, et al. MicroRNAs Related to Polycystic Ovary Syndrome (PCOS) Genes 2014;5:684-708.

Transcriptomic profiling of human embryonic stem cells upon cell cycle manipulation during pluripotent state dissolution.

While distinct cell cycle structures have been known to correlate with pluripotent or differentiated cell states [1], there is no evidence on how the cell cycle machinery directly contributes to human embryonic stem cell (hESC) pluripotency. We established a determinant role of cell cycle machineries on the pluripotent state by demonstrating that the specific perturbation of the S and G2 phases can prevent pluripotent state dissolution (PSD) [2]. Active mechanisms in these phases, such as the DNA damage checkpoint and Cyclin B1, promote the pluripotent state [2]. To understand the mechanisms behind the effect on PSD by these pathways in hESCs, we performed comprehensive gene expression analysis by time-course microarray experiments. From these datasets, we observed expression changes in genes involved in the TGFβ signaling pathway, which has a well-established role in hESC maintenance [3], [4], [5]. The microarray data have been deposited in NCBI's Gene Expression Omnibus (GEO) and can be accessed through GEO Series accession numbers GSE62062 and GSE63215.

MicroRNA dynamics during human embryonic stem cell differentiation to pancreatic endoderm

MicroRNAs (miRNAs) are small non-coding RNAs that have emerged as critical regulators of human embryonic stem cell (hESC) pluripotency and differentiation. Despite the wealth of information about the role individual that miRNAs play in these two processes, there has yet to be a large-scale temporal analysis of the dynamics of miRNA expression as hESCs move from pluripotency into defined lineages. In this report, we used Next Generation Sequencing (NGS) to map temporal expression of miRNAs over ten 24-hour intervals as pluripotent cells were differentiated into pancreatic endoderm. Of the 2042 known human miRNAs, 694 had non-zero expression on all 11days. Of these 694 miRNAs, 494 showed statistically significant changes in expression during differentiation. Clusters of miRNAs were identified, each displaying unique expression profiles distributed over multiple days. Selected miRNAs associated with pluripotency/differentiation (miR-302/367 and miR-371/372/373) and development/growth (miR-21, miR-25, miR-103, miR-9, and miR-92a) were found to have distinct expression profiles correlated with changes in media used to drive the differentiation process. Taken together, the clustering of miRNAs to identify expression dynamics that occur over longer periods of time (days vs. hours) provides unique insight into specific stages of differentiation. Major shifts in defined stages of hESC differentiation appear to be heavily dependent upon changes in external environmental factors, rather than intrinsic conditions in the cells.

Abstract LB-138: Use of cerebral organoids to model pediatric gliomas with H3.3K27M and H3.3G34R

Abstract Glioblastoma (GBM) is the most devastating brain cancer with dismal prognosis both in adults and children and accounts for 16% of primary brain tumors. Despite aggressive therapeutic approaches, the majority of patients die within one year after diagnosis. Giving the limitation of current GBM mouse models, which do not reflect the biological properties of human tumors, in particular, tumor heterogeneity and pathogenesis, there is a growing need for new models. Current in vitro 3D models involve the use of hydrogel scaffolds and cell lines, which do not represent a viable developmental context where the tumor mass interacts with and invades the surrounding brain tissues. Starting with pluripotent human embryonic stem cells we reproduced a 3D tissue structure (so-called cerebral organoid) representing a developing human brain in vitro. We engineered these mini-brains to express oncogenic hits responsible for the derivation of tumors in pediatric GBM patients. Pediatric GBM is driven by a combination of epigenetic and genetic hits including the expression of a mutant histone H3 variant H3F3A (mutated at K27M or G34R) or a gain of function mutant isocitrate dehydrogenase IDH1R132H in combination with the loss of the histone remodeling factor ATRX and/or p53 tumor suppressor. We used a combination of these oncogenic hits to create a model of tumor engineering representing the first 3D human tissue model of GBM. This model combines the accurate multi-lineage differentiation and physiology of human brain with the easiness of manipulation of in vitro systems. H&amp;E staining of the modified organoids shows remarkable dysplasia reminiscent of human primary glioma. Different genetic hits result in different type of dysplasia with IDH1R132H showing distinct morphology, suggestive of a broad range of applicability to model oncogenic-dependence in pediatric GBM. Cerebral organoids may also be used as a model to study tumor invasion starting with glioma stem-like cells (GSCs, which are believed to be the tumor-initiating cells in GBM). Indeed 923 GSCs (which are not invasive in mice brain) quickly and spontaneously (within few days) invade a co-cultured cerebral organoid. This study is the first to engineer a human CNS tumor in vitro. The model carries a tremendous potential to uncover the pathogenesis and initiation of brain cancer in pediatric settings. Citation Format: Amin Ismail. Use of cerebral organoids to model pediatric gliomas with H3.3K27M and H3.3G34R. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-138. doi:10.1158/1538-7445.AM2015-LB-138

Mesenchymal Stromal Cell-Like Cells Set the Balance of Stimulatory and Inhibitory Signals in Monocyte-Derived Dendritic Cells.

The major reservoir of human multipotent mesenchymal stem/stromal cells (MSCs) is the bone marrow (BM) with the capability to control hematopoietic stem cell development. The regenerative potential of MSCs is associated with enhanced endogenous repair and healing mechanisms that modulate inflammatory responses. Our previous results revealed that MSC-like (MSCl) cells derived from pluripotent human embryonic stem cells resemble BM-derived MSCs in morphology, phenotype, and differentiating potential. In this study, we investigated the effects of MSCl cells on the phenotype and functions of dendritic cells (DCs). To assess how antiviral immune responses could be regulated by intracellular pattern recognition receptors of DCs in the presence of MSCl cells, we activated DCs with the specific ligands of retinoic acid-inducible gene-I (RIG-I) helicases and found that activated DCs cocultured with MSCl cells exhibited reduced expression of CD1a and CD83 cell surface molecules serving as phenotypic indicators of DC differentiation and activation, respectively. However, RIG-I-mediated stimulation of DCs through specific ligands in the presence of MSCl cells resulted in significantly higher expression of the costimulatory molecules, CD80 and CD86, than in the presence of BM-MSCs. In line with these results, the concentration of IL-6, IL-10, and CXCL8 was increased in the supernatant of the DC-MSCl cocultures, while the secretion of TNF-α, CXCL10, IL-12, and IFNγ was reduced. Furthermore, the concerted action of mechanisms involved in the regulation of DC migration resulted in the blockade of cell migration, indicating altered DC functionality mediated by MSCl cell-derived signals and mechanisms resulting in a suppressive microenvironment.

Proteomic Analysis of Human Pluripotent Stem Cell-Derived, Fetal, and Adult Ventricular Cardiomyocytes Reveals Pathways Crucial for Cardiac Metabolism and Maturation.

Differentiation of pluripotent human embryonic stem cells (hESCs) to the cardiac lineage represents a potentially unlimited source of ventricular cardiomyocytes (VCMs), but hESC-VCMs are developmentally immature. Previous attempts to profile hESC-VCMs primarily relied on transcriptomic approaches, but the global proteome has not been examined. Furthermore, most hESC-CM studies focus on pathways important for cardiac differentiation, rather than regulatory mechanisms for CM maturation. We hypothesized that gene products and pathways crucial for maturation can be identified by comparing the proteomes of hESCs, hESC-derived VCMs, human fetal and human adult ventricular and atrial CMs. Using two-dimensional-differential-in-gel electrophoresis, 121 differentially expressed (>1.5-fold; P<0.05) proteins were detected. The data set implicated a role of the peroxisome proliferator-activated receptor α signaling in cardiac maturation. Consistently, WY-14643, a peroxisome proliferator-activated receptor α agonist, increased fatty oxidative enzyme level, hyperpolarized mitochondrial membrane potential and induced a more organized morphology. Along this line, treatment with the thyroid hormone triiodothyronine increased the dynamic tension developed in engineered human ventricular cardiac microtissue by 3-fold, signifying their maturation. We conclude that the peroxisome proliferator-activated receptor α and thyroid hormone pathways modulate the metabolism and maturation of hESC-VCMs and their engineered tissue constructs. These results may lead to mechanism-based methods for deriving mature chamber-specific CMs.